Now that we have serious third-party challenges, we need an instant runoff ballot to avoid dilemmas like spoiler, wasted vote and winners by plurality. An instant runoff ballot would allow voters to express their second, third and fourth preferences and have them count if their most preferred candidate has a low count in the first count of the ballots.
On the second count, low candidates would be eliminated and the second preferences of their first-preference supporters would be counted toward their second-preference candidate. More eliminations would continue until a candidate would achieve a majority. The idea is that instant runoff voting is a runoff election mechanism which can be done instantly with one visit to the polls and with no extra expense of an additional time-delayed runoff election campaign.
Many jurisdictions within the United States and many foreign countries make provision for runoff elections if no candidate receives a majority. In Australia, instant runoff voting is used to elect the Senate, and in Ireland instant runoff voting is used to elect the president. Some local community board and school board elections in New York City provide for expression of lower preferences. By being sensitive to voters second, third and fourth preferences the instant runoff would give voters enough confidence to vote their true first preferences first without fear of wasting their vote. Also, no candidate could be accused of being a spoiler because the second, third and fourth preferences of their supporters would count should they be eliminated in the early counts.
Also, a winning candidate would have to eventually achieve support of a majority of voters, preventing winning of the election by a plurality just because opposition is so divided.